Master Autofs Map

The auto_master map associates a directory with a map. The map is a master list
that specifies all the maps that autofs should check. The following example
shows what an auto_master file could contain.

Example 6–3 Sample /etc/auto_master File

This example shows the generic auto_master file
with one addition for the auto_direct map. Each line in
the master map /etc/auto_master has the following syntax:

mount-point map-name[mount-options]

mount-point

mount-point is the full
(absolute) path name of a directory. If the directory does not exist, autofs
creates the directory if possible. If the directory exists and is not empty,
mounting on the directory hides its contents. In this situation, autofs issues
a warning.

The notation /- as a mount point indicates that this
particular map is a direct map. The notation also means that no particular
mount point is associated with the map.

map-name

map-name is the map autofs uses to
find directions to locations, or mount information. If the name is preceded
by a slash (/), autofs interprets the name as a local file. Otherwise, autofs
searches for the mount information by using the search that is specified in
the name-service switch configuration file (/etc/nsswitch.conf).
Special maps are also used for /net. See Mount Point /net for more information.

mount-options

mount-options is an optional, comma-separated
list of options that apply to the mounting of the entries that are specified
in map-name, unless the entries in map-name list other options. Options for
each specific type of file system are listed in the mount man page for that
file system. For example, see the mount_nfs(1M) man page for NFS-specific
mount options. For NFS-specific mount points, the bg (background)
and fg (foreground) options do not apply.

A line that begins with # is a comment. All
the text that follows until the end of the line is ignored.

To split long lines into shorter ones, put a backslash (\)
at the end of the line. The maximum number of characters of an entry is 1024.

Note –

If the same mount point is used in two entries, the first entry
is used by the automount command. The second entry is ignored.

Mount Point /home

The mount point /home is the directory under
which the entries that are listed in /etc/auto_home (an
indirect map) are to be mounted.

Note –

Autofs runs on all computers and supports /net and /home (automounted home directories)
by default. These defaults can be overridden by entries in the NIS auto.master map or NIS+ auto_master table, or
by local editing of the /etc/auto_master file.

Mount Point /net

Autofs mounts under the directory /net all
the entries in the special map -hosts. The map is a built-in
map that uses only the hosts database. Suppose that the computer gumbo is
in the hosts database and it exports any of its file systems. The following
command changes the current directory to the root directory of the computer gumbo.

% cd /net/gumbo

Autofs can mount only the exported file systems
of host gumbo, that is, those file systems on a server
that are available to network users instead of those file systems on a local
disk. Therefore, all the files and directories on gumbo might
not be available through /net/gumbo.

With the /net method of access, the server name
is in the path and is location dependent. If you want to move an exported
file system from one server to another, the path might no longer work. Instead,
you should set up an entry in a map specifically for the file system you want
rather than use /net.

Note –

Autofs checks the server's export list only at mount
time. After a server's file systems are mounted, autofs does not check with
the server again until the server's file systems are automatically unmounted.
Therefore, newly exported file systems are not “seen” until the
file systems on the client are unmounted and then remounted.